[R-390] Filter Options II

[Cecil]

I would expect NOS filters to be about like NOS paper and electrolytic caps....to have aged just the same as an in service part...and possibly worse.  

Just my thoughts though...

Cecil

Sent from my iPad

On Feb 18, 2013, at 8:47 AM, Bob Camp <ham at kb8tq.com> wrote:

> Hi
> 
> They sold a *lot* of those IF decks with filters on them. A lot of people bought "more than one" for spares. I certainly did. I have absolutely no idea what shape the filters are in. I'll dig into them when I loose a filter….
> 
> Bob
> 
> On Feb 18, 2013, at 9:17 AM, djed1 at aol.com wrote:
> 
>> Probably a lot of filters out there- I have a set of spare filters stashed away.  What I don 't know is whether they are deteriorating as they sit in the box.  My R-390A has been in my possession for 30 years and has  seen light use all that time.  I hope that the deterioration of the foam in the filters is somewhat related to the operating temperature.
>> Ed  W2EMN
>> 
>> 
>> 
>> -----Original Message-----
>> From: Bob Camp <ham at kb8tq.com>
>> To: r-390 at mailman.qth.net Group <r-390 at mailman.qth.net>
>> Sent: Sun, Feb 17, 2013 10:14 pm
>> Subject: Re: [R-390] Filter Options II
>> 
>> Hi
>> 
>> I keep coming back to another option:
>> 
>> How many IF modules are there still out there? The world was awash in them a 
>> while back. I have a suspicion there are many more out there than one might 
>> think.
>> 
>> Bob
>> 
>> On Feb 17, 2013, at 5:00 PM, Perry Sandeen <sandeenpa at yahoo.com> wrote:
>> 
>>> List,
>>> 
>>> Wrote: With the exception of watch crystals, the whole industry of sub 1 MHz
>> crystals is pretty much a thing of the past. Yes, there are a couple of people 
>> who will make you this or that. You better have deep pockets to get them 
>> interested in whatever you need done. Yes, one of them is a buddy, but that only 
>> goes just so far.
>>> 
>>> Yea verily.
>>> 
>>> My take of the group’s replies is that:
>>> 
>>> 1. Crystal filters are out of the question unless one does and up
>> converter/down converter to use some of the commercial filters used in the rice 
>> box radios.  Probably a real PITA.
>>> 
>>> 2.  While ceramic filters can be used, the supply is probably extremely
>> limited, even worse that getting a original Collins replacement filter for the 
>> “A”.
>>> 
>>> 3.  Use the Lankford roofing filter mod and stick to a 6 KHz or less
>> bandwidth. For a $100 or so it is probably the most cost/time effective 
>> solution.
>>> 
>>> 4.  Convert your “A” to a R-725 and selling your remaining good filters on
>> epay to help offset the conversion cost.  Takes a lot of time and patience to 
>> convert the I.F. to 6 volt filaments. (Yes Tisha, I have 3 to do when I get 
>> a-round-to-it.)
>>> 
>>> 5.  Something microprocessor based would be too complex for the vast majority
>> of us.
>>> 
>>> Regards,
>>> 
>>> Perrier
>>> 
>>> 
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